The purpose of this investigation is to discover a system in the procaryote E. coli with which to study the mechanisms and regulations of protein degradation. To this end, growing E. coli were perturbed by starvation for a carbon or nitrogen source, or by conditions designed to provoke the "stringent response". As confirmed in this laboratory, these conditions have been shown to increase protein degradation as measured by the release of radiolabelled amino acids from intact proteins. The intent of this investigation is to specify which proteins are degraded and how the process is controlled. Techniques utilized have exploited polyacrylamide gel electrophoresis, isotopic studies, and the enzymatic assay of functional proteins.